1. Field of the Invention
This invention relates to apparatus for treating upright surfaces, for example ship hulls, silo walls, oil storage tanks and the like, with cleansers (e.g., detergent, sandblast sprays) and conserving materials (e.g., paint).
2. The Prior Art
Structures of the type mentioned above are usually made of steel and their surfaces are therefore subject to damage from corrosion. To prevent this, these surfaces are coated with corrosion-preventing media--such as paint or the like--which protect them. Before this can be done, however, the surfaces must be thoroughly cleaned--e.g., by washing, sandblasting or in other ways--because otherwise the corrosion-protecting media are not able to properly fulfill their intended purpose.
To manually effect such cleaning and later to apply the corrosion-protecting media, is extremely time-consuming, labor-intensive and hence costly. Equipment has therefore been developed for this purpose.
These devices have a carriage which travels horizontally along a support extending along the surface to be cleaned; for example, in the case of a ship hull the carriage travels along the upper edge of the dock wall where the hull is berthed. An outrigger arm projects laterally from the carriage and is turnable relative thereto about a vertical axis. Projecting from the outrigger and turnable relative to the same about a vertical and a horizontal axis, is a mast which carries at its free end an L-shaped support or which working devices, e.g., spray equipment, sand or grit-blasting equipment or the like, are directly mounted. This has been found not to be entirely satisfactory, because the equipment tends to shift out of its selected position and the transmission of forces during movement about the respective horizontal and vertical axes, is not favorable.